This invention relates generally to freestanding structures such as tents and the like.
For thousands of years, large-scale tensioned fabric structures have been used as shelter and protection for groups of people. Large-scale structures pre-date the smaller versions, typically used by two or three people, which were designed only in the last few centuries. Innovations and improvements have modernized virtually every aspect of the smaller versions and currently the field of invention for these structures is very crowded and a minor advance carries great weight. Despite the overcrowding of patentable art in the field of small structures, most of these improvements have not been practiced on larger-scale structures, leaving these designs crude in comparison. It has been more than 30 years since large-scale design having today""s widest commercial and industrial acceptance was developed.
All present-use tensioned fabric structures utilize some sort of weight-bearing pole framework which forms a skeleton upon which the fabric cover is suspended. As such, the pole framework performs the function of supporting the fabric weight and the fabric cover performs the separate function of establishing the structure""s sheltering walls and roof. In prior-art structures, the two functions work against each other to create the tension referred to in the generic Class of this invention, xe2x80x9cTensioned fabric structuresxe2x80x9d. In the author""s opinion, all prior-art design wrongly separates these two functions into opposing roles. By not integrating the support and covering functions in a cooperative, co-active role, present-use structures suffer from a number of disadvantages. My prior U.S. Pat. No. 5,343,887 describes the disadvantages suffered in the field of small-scale structures; this present invention addresses the various types of problems suffered by large-scale structures.
One of the principal problems with large-scale structures is that associated with erecting them. The assembly process is complicated and exacting, rendering set-up by one person impossible and often three or more persons are required. The process involves unpacking a bewildering assortment of pole segments, stakes, guy-lines and an enormous flaccid fabric cover which is many times bigger than, and has no apparent relationship to, the structure""s final set-up shape. The most rudimentary embodiments require a minimum of six vertical rods (each of which is typically longer than five feet), at least three horizontal support poles (each usually has a length of more than seven feet), and several (the simplest structure requires eight) stakes and/or guy-lines. The set-up and trimming process guarantees that the assembly procedure of all prior-art large-scale structures is never the same twice, each is a laborious and custom installation. If the users suffer from lack of experience or a momentary negligence, they may upset the delicate balance of the partially-erected structure at any time during the set-up procedure, causing them to start again and all their progress lost. Furthermore, if any one of the components is lost, torn, broken or misplaced, set-up of these prior-art structures could be impossible.
Present-use large-scale design requires users to anchor the fabric cover to the terrain with stakes, guy-lines or the like. This is a second handicap as such structures are incapable of being relocated after they are assembled. The tensioned support is violated when any stake, rod or other anchoring mechanism is moved; relocating involves dismantling the frame and extensive anchoring means and rebuilding from the beginning. Structures lacking freestanding capability are also unsuitable for scree, rocky or sandy terrain.
The weight of prior-art large-scale structures is a third liability which smaller-structure design has attacked zealously. It is not uncommon for a smaller structure accommodating two users to weigh as little as three or four pounds while larger structures accommodating six users can weigh more than sixty pounds. The inefficient distribution of stresses in large-scale prior-art design, caused by separating the support function from the covering function as described previously, feeds a vicious circle of ever-increasing weight: heavier framing members require heavier fabrics which in turn require enhanced frame support, calling for still heavier fabrics, etc., etc., etc. Further, present-use designs strengthen stress areas assiduously with weighty reinforcement means. Additional support poles, rods, stakes and/or guy-lines to relieve the fabric of poorly diffused stress add further weight, complexity and expense.
The high cost of present-use structures is a fourth significant detriment. Because the supporting and covering functions are set in opposition, stresses inherent in large-scale design require framing members and fabrics not only heavier but also much more costly than necessary. Poles and rods are generally expensive components and heavier versions are even more costly to produce, ship and warehouse. Workmanship to cut and handle brawnier fabrics is more complicated and sewing is much more difficult. Reinforcing large areas as described increases manufacturing complexity and expense. Workmanship to attach myriad stakes, guy-lines and another anchoring means increases manufacturing costs while purchasing additional parts requires expensive outsourcing.
All prior-art large-scale fabric structures suffer a fifth and final drawback regarding their limited range of sizes and/or shapes. Present-use large structures are square or slightly rectangular; to erect larger structures or to utilize shapes other than these limited options introduces an entirely new level of complexity which is evidenced at outdoor events and the like where typically rented facilities accommodating larger groups of people involve an experienced full-time staff of many members and usually a full day for set-up or disassembly.
It is unfortunate that the designs of smaller-scale support structures, including their innumerable variants, can not be adapted for large-scale embodiments. Smaller-scale structures utilize bowed poles to place the fabric cover under tension; users skilled in the art recognize the difficulty and possible danger of bending enlarged support poles if adapted for use with larger-scale structures which typically use rigid and inflexible frame members. Also, smaller designs, if adapted, would lack basic functional capability: the simplest embodiments utilizing two or three support poles are undependable in ordinary winds without profuse anchoring, larger versions of these designs would be totally implausible. Designs of more elaborate smaller-scale embodiments utilize semispherical pole formations which employ arc trigonometry formulae that cannot be adapted if a low profile structure is required. These disadvantages, developed further in the following sections, effectively eliminate the possibility to adapt the myriad designs of small-scale embodiments for use as large-scale structures and today no such versions are recognized commercially.
Large-scale, freestanding tension structures which do not employ the inefficient support structure described previously have been disclosed in the prior art. My U.S. Pat. No. 5,343,887 describes a stable, lightweight, easy to assemble, portable fabric structure which eliminates weight-bearing support poles and rods by utilizing an end panel at each end, comprised of resilient strip material formed into a single hoop secured to flexible fabric covering and maintained in generally upright position by at least one spreader rod extending between the end panels. The end panels preferably have circular hoops, yet circles, by definition, are as tall as they are wide so by enlarging such structures the height and width are coequally increased. Thus the invention of my U.S. Pat. No. 5,343,887 is intended primarily or small-scale structures rather than for large-scale embodiments where height becomes a limiting factor.
A circular framing member can be made oval as described in my U.S. Pat. No. 5,343,887 by increasing tension along its horizontal axis. Utilizing an oval frame member provides for a shorter and wider structure than an embodiment utilizing a circular framing member. However, after exceeding a limited and invariable horizontal-to-vertical ratio, an oval framing member suffers loss of capability as the fabric-covered oval fails to supply any weight-bearing role without distortion or collapse. This ratio is approximately two-to-three (height-to-width) or to put this in other words: if one wants a structure utilizing prior U.S. Pat. No. 5,343,887 one will have a structure two-thirds as tall. While contributing an incremental enhancement vis-à-vis the author""s circular embodiment, the limited capability of oval framing members nevertheless limits the possible size of any functionally operable structure described in my U.S. Pat. No. 5,343,887 especially if structures with substantially low profiles are required.
My U.S. Pat. No. 5,343,887 discloses a structure with two fabric end panels, each provided with a single hoop sewn or in any manner attached to the fabric. The hoops are twisted and collapsed when the tent is prepared for storage, and this can be done easily if the tent is not too large. For larger embodiments utilizing larger hoops, the hoops must be twisted several times to reduce the overall size for storage, and this can be quite difficult considering the weight and bulk of the fabric.
In accordance with my present invention, the end panel(s) is provided with two or more hoops rather than just one. Plural hoops relatively small in diameter can be even more effective than one large hoop and are much easier to handle when twisted for storage, especially for large-scale structures.
Several advantages of the present invention are:
1. Novel Support Element:
My invention uniquely integrates the support and cover functions by means of novel fabric-covered hoops which act as the weight-bearing support element while simultaneously forming the structure""s covering end panels. Unlike poles which can bear weight by themselves, the hoops have a tendency to sag into an oval under the slightest load. However, the hoop incorporates a taut non-stretch fabric attached generally at all points to its perimeter, constricting it and thereby preventing sagging. This integrated fabric-covered hoop maintains its original shape despite bearing considerable weight and is a key advancement in the art of fabric-tensioned structures.
2. Easier and Speedier Assembly:
My invention eliminates all of the principal complications in the assembly of prior-art large-scale design:
The user shakes the collapsed structure of my invention and the resilient hoops virtually xe2x80x9cself erect.xe2x80x9d Because these hoops constitute essential parts of opposite end walls, it is uniquely easy to recognize the final shape of the structure during the assembly process.
The fabric-covered hoops of my invention, forming the end walls as described, stand erect by themselves and thus make irrelevant the need to lift end wall fabric during assembly. The self-standing hoops also support the weight of the structure""s roof, therefore the complex process of lifting and setting up prior-art structures is greatly simplified.
In short, the design of my invention allows for a large scale structure to be assembled in the shortest possible time and with the fewest people. The structure can be set up by novice users. The tedious xe2x80x9clearning curvexe2x80x9d associated with other structures is eliminated. As well as easily introducing new users to the sport of outdoor camping, the simplicity of assembly also enables the structure of my invention to be used as shelter for groups in emergencies. Ease of assembly is crucial in inclement or severe environments or where users are setting up the structure for the first time.
3. Structurally Capable in any Size:
The end panels of my invention can be adapted in a wide variety of configurations to provide for structures of any size. By utilizing more than a single hoop at the structure""s end panel, the tent can be enlarged without increasing its height. Two adjacent hoops, for example, double the structure""s width, three hoops triple it, etc.
The end panels can be still further adapted in a wide variety of configurations to provide specific advantages without compromising the objects of the invention. The preferred embodiment establishes multiple hoops in a generally adjacent and approximately flat end panel in-use configuration. Multiple hoops can also be configured to form a wedge or similarly shaped non-flat end panel to provide for increased internal space and/or windworthiness. The end panel can also be further adapted to provide for even larger structures: additional fabric can be provided in the space(s) between the multiple hoops to enlarge the width of the tent without increasing the height; hoops positioned above one another allow for taller structures if required. Moreover, the end panel or at least one of the multiple hoops therein can be inclined and/or the acclivity of one or both sidewalls increased to maximize floor space. These adaptations do not alter any of the tent""s structural components nor compromise any of the invention""s capabilities.
4. Freestanding:
The tent of my invention in some embodiments requires no stakes or guy-lines running to outlying stakes to establish structural support. These anchors typically suffer the obvious disadvantage of coming loose either by the tent working the wind or by the user tripping over them during darkness. My invention is suitable for rocky or sandy terrain or impenetrable hardpan, also the orientation can be rapidly changed under varying weather conditions if necessary.
5. Stronger:
As is well known to those skilled in the art, circles, ellipses and arches disburse weight evenly and with great stability. The end panels of my invention easily distribute the considerable weight of the covering fabric of a large-scale structure. Stresses common to prior-art tents are distributed naturally throughout the hoop(s) so stress points and compensating reinforcement are minimized.
A user can lean on the walls of my invention and the hoops will move to absorb stress from any direction. It is practically impossible to break the integrated fabric-cover hoop so the chances of collapse or permanent damage to the tent are minimized.
Further, the circular design of my invention deflects loads caused by rain, wind, ice rime and/or snow. As disclosed previously, the invention can be altered for increased wind worthiness without changing the tent""s structural components. By inclining one or both end-walls of the structure and/or increasing the acclivity of the sidewalls, the target size of the structure is reduced for extra dependability in deflecting heavy wind loads and to facilitate shedding of snow and wind-driven rain in inclement weather.
6. More Internal Space with Less Material:
Nature""s most efficient shape (maximum internal volume with minimum surface area) is a sphere. Due to the novel circular-based hoop design of the end panels, my invention encloses more cubic living space per given amount of fabric than any prior-art tension structure. Putting this another way, to provide a structure of given internal size, an advantage of my invention is that it requires less fabric.
7. Lighter:
Fabric-covered hoops distribute stress evenly throughout the hoop""s perimeter so lighter fabrics can be adopted and reinforcing minimized. Also, as previously described, a structure of any particular size can be made with a minimum of fabric thus reducing a principal factor contributing to a structure""s weight.
8. Full Use of height, Increased Headroom and Floor Use:
Prior-art designs allow the user to stand erect in only a small central or apex portion of the structure. The consistent, uniform height of my invention eliminates any such apex and provides for uncompromising utilization of the structure""s full height throughout the entire length of the structure.
My invention""s circular design further provides increased headroom as its shape correlates to the space used by a users"" upper body movements.
Many, but not all embodiments of my invention provide rectangular or square floors correlating to the shape of the users"" sleeping bags and related equipment. Sleeping bags and user gear may be pushed all the way to the edge of the structure if desired because the vertical sidewalls allow for optimum use of the floor area.
9. Fewer Components:
Because the fabric-covered hoop is both the support element and also the structure""s end walls, my tent requires far fewer support members compared to prior-art tents. Fewer parts can be broken or misplaced; complexity during set-up, teardown and in-use is reduced; maintenance is minimized. In some embodiments, rods and poles are completely eliminated; in other embodiments, only a single rod is utilized. In still further embodiments, no sleeves, stakes, tie members, flaps, straps, grommets, buckles or guy-lines are needed.
10. Ease of Production:
The consistent height of my invention reduces the number of separate fabric pieces and minimizes workmanship in cutting and sewing of irregular fabric patterns. Additionally, full widths of material can be utilized eliminating fabric waste. Costly reinforcements to counteract fabric stresses are substantially reduced as are the needs for support means and anchoring means as mentioned above.
11. Less Expensive:
Due to the superior strength and efficiency of the hoop design, the capability to utilize lighter, less expensive fabrics and to minimize fabric waste in production, ease of cutting and sewing, the reduced need for support members, etc., as described, the tent of my invention is less expensive to produce than all other large-scale prior-art fabric tension structures. Containerizing, shipping and insurance costs are correspondingly reduced.
12. Superior Compatibility:
The structure of my invention folds into a packed relatively flat disc by taking three turns in the manner described in prior U.S. Pat. No. 5,343,887. Instead of folding a very large single hoop, however, multiple smaller hoops are turned as a xe2x80x9choop groupxe2x80x9d into a readily portable flat circular configuration. Prior patent 5,343,887 describes tents which fold to one-third or one-ninth of the loop""s size when opened; the patent of my present invention can double or triple this factor and, in some embodiments, the structure folds to less than one-fiftieth the size of the end panel when opened.
One embodiment features an end panel which is releasibly attached to the covering fabric by means such as zippers or the like. When the end-panels are separated from the covering fabric, bulkiness during folding is reduced and nine hoops can be taken to provide for a smaller collapsed parcel. Weight of the packed disc is evenly distributed and balanced for ease of transport. In another embodiment, folding is facilitated by removing the hoops from the fabric sleeves of the end panel. The loops can be reinserted or end-panels reattached and the structure regains full structural capability and efficacy. Separating the hoop(s) from the fabric utilizing the two means as described above, either severally or in combination, allows for optimized folding and packing.
It is therefore, an object of the present invention to provide an improved fully freestanding, portable large-scale structure.
A second objective of this invention is to provide such a structure which can be erected readily by fewer users.
Another object of the invention is to provide a versatile large-scale structure which can be truly made in a plurality of sizes depending on design parameters.
Still another object of the invention is to provide a large-scale structure which can readily be folded into a compact size for storage and transportation purposes.
It is further an object of this invention to provide such a structure which is extremely simple and economical to manufacture.
It is a further object of this invention to provide a fully-accessible floor, increased headroom and greater cubic living space while using less fabric than prior structures.
It is still a further object to provide a large-scale structure light in weight.
A further object is the provision of a novel, inherently integrated design wherein fabric-covered loops support the structure""s weight and form its walls.
A still further object is to provide a rugged, essentially non-breakable large-scale structure.
A further object is to provide a stable, windworthy large-scale structure.
A still further object is the provision whereby a hoop, fabric therefore and cover cooperate to define a unitary assembly of unique design and decorative appearance.
The above and other objects are realized by the provision of a self-contained freestanding large-scale tension structure which in general terms comprises one or more end panels, at least one of which comprises two or more approximately adjacent hoops of flexible coilable resilient material and a flexible fabric cover extending between said panels. The end-panels, or hoops of flexible material therein, are held in a generally upright position preferably by a single segmented rod which exerts tension horizontally and in opposite directions.
The hoop is affixed. to a flexible fabric-like taut sheet material; more particularly, by securement at least at a plurality of points between the fabric and the hoop. Hoops are preferably endless and closed, but as described earlier in this patent, ends of the coilable strip material may be releasably connected to provide for removal of the loop from the fabric-like taut sheet material for ease of packing and storage.
The hoops can take on any of a wide variety of specific configurations. For example, the hoop can be compelled into an oval shape by increasing tension in its covering fabric in either the vertical or horizontal direction. Alternatively, the hoop can be fabricated into a circle, ellipse or arch shape. A hoop having one or more generally right-angle square corners in an otherwise circular or elliptical shape is possible. The loop may incorporate extension(s) running to the ground or to other parts of the end panel. Each embodiment offers separate advantages without compromising the objects of the invention.
The end panel flexible fabric cover can incorporate one loop style or shape or a combination of different styles without affecting the capability or operability of the structure. The integrated fabric-covered hoop maintains its weight-bearing capability when the hoop""s covering fabric incorporates openings or voids to provide access to the outside of the structure. One end panel may utilize two adjacent hoops and the other end more than two hoops and the structure collapses fully and suffers no loss of capability. The other end may also utilize fewer hoops or even none, for example when attaching the fabric cover to a separate structure to provide for a spare room. This adaptation provides for ultra-lightweight structures similar to tents known in the prior art as a xe2x80x9cbivvyxe2x80x9d. It should be understood that connections between adjacent hoops are preferable in some embodiments, but are not essential. Also, the two hoops of an end panel can be of different sizes if required.
The frame, as described, is held in the desired in-use configuration by a flexible fabric cover extending between the end panels. The fabric cover can take on a wide variety of specific configurations without compromising the invention. For example, in some embodiments, additional floor space can be provided by increasing the acclivity of the covering fabric side-walls. In other embodiments, the fabric floor can be eliminated. The structure can be adapted with openable and extendable side-wall(s) to provide for a cabana-like structure with shade-giving awning(s). The fabric can be further adapted to provide space between it and a separate or integrated rain fly. The end-panel can be releasably attached to the fabric cover, by means of a zipper or the like, to allow for the two components to be separated and folded independently for ultimate compactibility.
Because of the coilable nature of the hoop material and the flexibility of the fabric covering, the structure can be xe2x80x9ccollapsedxe2x80x9d in an orderly fashion by manipulating the loops in a simple manner as described in my prior U.S. Pat. No. 5,343,887. Upon collapse, the structure assumes a flat circular configuration which is readily portable and which virtually self-erects upon further manipulation.
Each of the above components, as disclosed in the preferred embodiment described in further detail below, can be altered without compromising the efficacy of the invention. For example, the framing means of the several embodiments are interchangeable. The diverse configurations of the fabric cover are practicable on any embodiment. Likewise, all of the end panel loop configurations of the several embodiments herein disclosed are interchangeable with one another.
The features, advantages, and objects of my invention which are explicit and implicit in the foregoing as well as others will become apparent and more fully understood from the following detailed description of the invention in connection with the accompanying drawings.